ipso-Cyclization of unactivated biaryl ynones leading to thio-functionalized spirocyclic enones

Abstract

Ceric ammonium nitrate (CAN)-promoted oxidative ipso-cyclization of unactivated biaryl ynones with S-centered radicals (SCN/SCF3) to access spiro-[5,5]trienones has been established. The approach displayed excellent regioselectivity towards spirocyclization and tolerated a...

Recent advances in radical thiocyanation cyclization or spirocyclization reactions

“…In 2023, Reddy completed a CAN-promoted oxidative spiro-cyclization of biaryl ynones to access SCN-containing spiro[5,5]trienones. 23 Next, the substrate tolerance was examined in detail (Scheme 31). Common functional group-revised biaryl ynones all could perform spirocyclization and provide the relevant spirocycles 77–80 in good yields.…”

Synthesis of Indenones via Persulfate Promoted Radical Alkylation/Cyclization of Biaryl Ynones with 1,4-Dihydropyridines

“…To date, the cyclization of alkynes toward the synthesis of cyclic compounds has been effectively investigated [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Recently, the radical cascade cyclization of biaryl ynones has been demonstrated to be a useful approach to construct six-membered spiro[5,5]trienones [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ] with the development of different types of radical precursors ( Scheme 1 a–c). For example, Chen and Zhou reported an iron-catalyzed cascade silyl radical addition/6- exo -trig cyclization/dearomatization of biaryl ynones with silane, affording silylated spiro[5.5]trienones in good yields [ 35 ].…”

“…For example, Chen and Zhou reported an iron-catalyzed cascade silyl radical addition/6- exo -trig cyclization/dearomatization of biaryl ynones with silane, affording silylated spiro[5.5]trienones in good yields [ 35 ]. In addition, several groups have demonstrated some elegant examples based on C-, N-, P-, S-, Si-, Se-centered radicals-induced cascade cyclization of biaryl ynones in the presence of transition-metal catalysts, oxidants or photocatalysts [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. For example, Duan and Yang reported the preparation of alkyl-functional spiro[5.5]trienone through alkylative dearomatization and the spirocyclization of biaryl ynones, respectively [ 29 , 33 ].…”